Final answer:
Age, gender, income, and weight can be categorized as either quantitative or categorical variables.
Step-by-step explanation:
a) Age: Age is a quantitative variable because it represents a numerical measurement. It can be measured and expressed using numbers. For example, someone's age can be 20 years old or 35 years old.
b) Gender: Gender is a categorical variable because it represents different categories or groups. It cannot be measured numerically. Gender can be expressed as male or female.
c) Income: Income is a quantitative variable because it represents a numerical measurement. It can be measured and expressed using numbers. For example, someone's income can be $50,000 or $100,000 per year.
d) Weight: Weight is a quantitative variable because it represents a numerical measurement. It can be measured and expressed using numbers. Someone's weight can be 150 pounds or 200 pounds.